Such a switching converter is already known in the art, e.g. from the book "Design of Solid-State Power Supplies" by Eugene R. Hnatek, published in 1981 by Van Nostrand-Reinhold, and more particularly on pages 562 to 581 thereof.
In a switching converter of this known type a very small error signal could lead to zero ON periods of the clock signal. As a consequence, the output signal of the duty cycle controller then presents a relatively large low frequency ripple producing considerable low frequency noise. The latter has an unwanted effect in systems operating in the low frequency band such as the voice frequency band in telephone systems.